Smooth with the rough

Polyurethane-based products ranging from wheelchair, wheelbarrow and bicycle tyres to building insulation foam are claimed to be more environmentally friendly as a result of new production processes from

.

One example is the collaboration between Bayer and Middlesborough company

to develop a tailor-made system for the production of the company's micro-cellular polyurethane tyres.

The tubeless tyre, claimed to be able to run over nails, metal shards or even broken glass without puncturing, are now being sold for wheelchairs, bicycles and light industrial use around the world. The tyres are produced in the UK and, according to the developer, created using a process that is clean, non-carcinogenic, chlorofluorocarbon-free and which releases no harmful toxins to damage the atmosphere.

The manufacturing process begins when a mould is filled with a liquid reaction mix before being rotated during the foaming process. The rotation ensures the material is distributed evenly across the whole tyre circumference.

'The rotation method also creates a special integral skin foam structure in which the density of the foam increases towards the outside of the tyre,' said Daniel Seidlitz, a specialist in polyurethane foam systems at Bayer. 'The material is virtually solid at the tyre's outer circumference, and its even surface makes for excellent rolling properties,' he added.